This invention relates to an orthotic device that limits the abduction of the legs while permitting normal adduction, differential rotation, extension and flexion, and particularly to an orthotic device to aid in correcting abduction while encouraging normal development of the hips and developmental movement patterns.
The hip is a ball and socket joint having motion in three axes. Normal development of the hip joint is directly dependent on the proper positioning of the femoral head in the acetabular socket and the motion of the joint in all three axes. One axis of motion of the hip joint is generally referred to as extension and flexion, and is the movement of the leg in a back-to-front orientation; extension being toward the back and flexion being toward the front. The second axis of the hip joint is referred to as abduction and adduction, and is the movement of the leg in the lateral (abduction) and medial (adductioia) directions; moving the legs laterally (abduction) tends to spread the legs whereas moving the legs medially (adduction) causes one leg to approach the other. The third axis is rotation with external rotation being that motion where the anterior portion of the leg rotates laterally (away from the other leg) and internal rotation being that motion where the anterior portion of the leg rotates medially (toward the other leg).
Development of the hip begins in utero and continues over approximately the first eight to nine years of a child""s life. With normal growth and development, compressive forces, first from crawling and then from walking, transmit through the hip from the femur to the pelvis generally increasing the depth of the acetabular socket and the formation of the femoral head. This cooperative development continues until normal acetabular depth is reached and the femoral head is formed to approximate a ball. To walk normally, a child must achieve sufficient strength and control to be able to achieve hip extension and flexion while bearing his or her own weight and maintaining a neutral position with regard to the second and third axes (abduction, adduction and rotation). In addition, the child must have good control of rotation.
Leg motion is not well controlled for some children with neuromuscular abnormalities. As a result, their legs may often be in a position of abduction. Consequently, anticipated hip development of the acetabular and femoral head may be affected due to persistent abnormal positioning. Without proper positioning, there is an increased risk that the hip joints may not develop sufficient depth for the needed stability. Stability may also be increased by the strengthening of the muscles around the hip joints when the legs are moving in supportive alignment.
In the past, it has been common to use a strap wrapped around the child""s legs to counteract the tendency for abduction of the legs. Such devices did little more than restrain the child, and did not contribute to the development of the hip joint through normal motion and forces through the hip associated with ordinary crawling and walking.
Woodman, in U.S. Pat. No. 5,718,672, proposed a device by which bands were fastened to the legs. An elastic strap interconnects the bands to urge the legs toward each other in adduction and internal rotation. Hence, the elastic interconnecting strap biased the legs to adduction and internal rotation and against abduction and external rotation. However, the Woodman device did not adequately promote extension and flexion of the legs associated with normal walking or crawling. Thus, the Woodman device retained the legs in a more neutral position and restricted extension, flexion and rotation as well as abduction. Children using the Woodman device experienced tugging on one leg as the other moved, such as when crawling or walking. Another difficulty with the Woodman device is that it inhibits differential rotation, namely simultaneous internal rotation of one leg and external rotation of the other leg, as in a twisting motion. Such motion is considered essential in the development of the normal movement patterns.
The present invention provides an orthotic device having first and second flexible bands each having anterior and posterior aspects relative the legs of the wearer. A fastener slidably fastens the first and second bands and includes first and second straps each having a first portion connected to the anterior aspect of the respective band and a second portion connected to the posterior aspect of the respective band. The straps are slidably connected together.
In a preferred form of the invention, the fastener includes a ring and the first and second straps are arranged as respective first and second loops passing through the ring.
In another preferred form of the invention, an adjustable connector fastens a portion of each flexible strap to the respective flexible band to adjust the size of the respective loop.
In one embodiment, the first and second flexible bands are arranged to be wrapped around the legs of the wearer. A band connector secures the flexible band to the leg. In another embodiment, the first and second flexible bands are integral with pant legs of a garment.
Optionally, tether straps connect a midportion of each flexible band adjacent the band connector to one end portion of the band. Also optionally, other tether straps connect each flexible strap to the respective band adjacent the adjustable connector.
Another aspect of the invention resides in a method of limiting abduction of the legs of a wearer while permitting extension, differential rotation, adduction and flexion of the legs. An orthotic device is provided having first and second flexible members and a fastener slidably fastening the first and second members. The fastener includes first and second straps each having a fir portion connected to the anterior aspect of the respective member and a second portion connected to the posterior aspect of the respective member. The straps are slidably connected together. The first and second members are attached to respective legs of the wearer. The fastener is then adjusted to establish a limit to abduction of the legs. Preferably, the first and second straps are adjustable loops, and the fastener is adjusted by adjusting a size of each loop.